Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P1/00—Auxiliary devices
  • H01P1/20—Frequency-selective devices, e.g. filters
  • H01P1/201—Filters for transverse electromagnetic waves
  • H01P1/205—Comb or interdigital filters; Cascaded coaxial cavities
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
  • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
  • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
  • H01J65/042—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field
  • H01J65/044—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels by an external electromagnetic field the field being produced by a separate microwave unit
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

• the present invention relates to a lamp to be driven from a source of microwave energy and having an electrodeless discharge bulb.
• a bulb positioned in a cavity within the body contains a gas- fill which when receiving energy from the resonating body forms a light-emitting plasma. (Despite reference to a "bulb", this specification does not describe a discrete bulb, separable from the lamp body.)
• the object of the present invention is to provide improved coupling of microwave energy to an electrodeless bulb in a lamp.
• a lamp to be driven from a source of microwave energy comprising:
• a bulb receptacle formed of ceramic material coated with an electrically conductive shield, the receptacle having: • a first recess containing the bulb, the recess being open to allow light to shine from the bulb and
• microwave coupler is • a capacitative-inductive circuit matching output impedance of the source of microwave energy to input impedance of the coupler, receptacle and bulb combination.
• the microwave circuit namely, the capacitative-inductive matching circuit can be a lumped element or tank circuit, preferably having discrete capacitor and inductor elements configured as a bandpass filter. Alternatively, it can be a comb line filter.
• the matching circuit is an air wave guide bandpass filter
• a wave guide based on other dielectric- materials may be used, for instance ceramic material.
• Such wave guide is described in US Patent No. 4,607,242.
• the circuit is-arranged to be tunable, not only to take account of small production variations between the bulbs and the filters themselves, but also to give the filter bandwidth to include the resonant frequency of the wave guide and bulb.
• the circuit comprises a pair of perfect electric conductors (PECs), each grounded inside a housing and each having a connection one for input and the other for output. Opposite the distal end of each PEC a tuning element is provided and a further tuning element is provided in the iris between the PECs.
• PECs perfect electric conductors
• the bulb receptacle can be a resonant wave guide.
• it is a half wave, wave guide or a quarter wave, wave guide in the interests of space saving.
• other configurations such as a full wave, wave guide can be envisaged.
• it is of a material having a dielectric constant greater than one.
• it will be of ceramic material.
• Figure 1 is a perspective view of a lamp with a bandpass filter in accordance with the invention
• Figure 2 is a central longitudinal cross-section in plan of the lamp
• Figure 3 is a central longitudinal cross-section in elevation of the lamp;
• Figure 4 is a plot of V SWR (Voltage Standing Wave Ratio) response to input frequency with varying frequency of the band pass filter alone;
• Figure 5 is a similar plot of the combination of the band pass filter and the wave guide with its lamp prior to lighting of the bulb;
• Figure 6 is another similar plot of the combination after lighting of the bulb;
• Figure 7 is perspective view of an exemplary bandpass filter of the invention;
• Figure 8 is a side view of the filter of Figure 7;
• Figure 9 is a further side view of the filter;
• Figure 10 is a cross-sectional side view on the line IX-IX in Figure 9.
• a band pass filter 1 is comprised of a resonant, air filled aluminium chamber 2, having a lid 3, together defining a cuboid resonant cavity 4 having a central 1 iris 5.
• PECs perfect electric conductors
• One is connected to a feed wire 8 from an input 9 at one end of the cavity.
• the other PEC is connected via a further feed 10 wire to a radiator 11 in an adjacent wave guide 12.
• Threaded tuning projections 14, 15 opposite the PECs and 16 in the iris are provided, whereby the pass band and the transmission characteristics of the filter in the pass band can be tuned to match the input impedance of the band pass filter and the wave guide to the output impedance of a microwave drive circuit (not shown).
• the impedance will be 50 ⁇ .
• the wave guide 12 is of ceramic and metallised on its outer surfaces. It is mounted on one end of the filter chamber, with an electrodeless bulb 21 in a central cavity 22 directed axially away from the chamber and the radiator in a further cavity 23 set to one side of the central cavity.
• This arrangement is a lamp.
• the arrangement is such that the filter has a pass band including the resonant frequency of the wave guide, conveniently when resonant in the half wave mode. When the filter is driven, the wave guide resonates driving the bulb.
• the input impedance, of the combined matching circuit and ceramic wave guide with its bulb is such that the microwaves at the design frequency are transmitted inwards of the input with negligible reflection. Waves reflected from the ceramic wave guide are reflected back into the wave guide from the output of the matching circuit and are not transmitted through the matching circuit for propagation back towards the drive circuit.
• the PECs 6,7 are similar to each other and have their tuning projections 14,15 aligned with their distal ends.
• the input PEC 6 is tuned to produce the low VSWR frequency spike Fl and the output PEC 7 is tuned to produce the high frequency spike F2.
• the levels and frequencies of the spikes can be controlled individually, although it will be appreciated that the adjustment of one has an effect on the other.
• the width of the pass band is primarily controlled by the iris tuning projection 16.
• Figure 4 shows the VSWR response of the filter alone
• Figure 5 shows its response when the wave guide and the bulb of the lamp are connected to it.
• An additional VSWR spike having a frequency F3 between Fl and F2 is introduced. This is at the resonant frequency of the wave guide.
• F3 between Fl and F2
• the lamp has been driven by microwave energy having a frequency within the pass band and with sufficient intensity to cause ionisation of the contents of the bulb, this represents a short circuit to the energy, absorbs it and emits light.
• the frequency at which the ionisation can be maintained is less specific and the VSWR response, as shown in Figure 6 widens, particularly at the higher frequency end.
• FIGS 7 to 10 show a practical example of a matching circuit in accordance with the invention and suitable for driving a half wave ceramic wave guide at 2.4 GHz.
• It comprises a square block 101 of aluminium 39.9 x 39.9mm. It has 6.0mm thick side plates 102 screwed to it by ten screws 103 each. These are uniformly positioned, taking account of tuning screws 104 and connectors described below.
• the tuning screws are in one side 105 of the block, which has a wall thickness of 5.84mm.
• End walls 110, 111 between the side walls 105, 107 are 6.60mm thick, that is in cross-section from the central cavity to the outside. All of the walls have a height - perpendicular to the 6.60mm thickness - of 16.04mm.
• the PECs 108,109 are 5.04mm thick in the direction of the 16.04mm height and 4.28mm thick in the direction of the 6.60mm thickness of the side walls 105,107.
• the PECs are positioned at mid-height of the block in the direction of the height of the side walls. Also they are equally spaced from at 3.15mm and parallel to the side walls. Thus they have an iris gap between them of 11.84mm.
• Extending into the central cavity from the opposite direction, i.e. from the tuning side wall 105 is a full height iris ear 112 centrally placed and 5.70mm thick. It extends 5.28mm into the cavity. From the opposite side wall, the PECs extend 26.54mm.
• the block, the PECs and the iris ear are all machined from solid. AU internal corners are radiused 1.5mm.
• the tuning screws are received in finely tapped bore inserts 113 aligned with the central axes of the PECs.
• the thread is 1 A inch by 64 threads per inch UNS, which is a very fine thread and allows fine adjustment of the characteristics of the circuit.
• the end walls are tapped to receive screws 115 for input and output connectors 116. These have central wires 117 which pass direct to the PECs 3.26mm from the inside face of the opposite side walls.
• the PECs are drilled 1.3mm to receive wires 117. These are soldered in position.
• the skin inside of the aluminium block and the side plates can be plated with very high conductivity metal such as silver or gold.
• very high conductivity metal such as silver or gold.
• the skin depth is 2 microns. Plating to 6 or 10 microns provides amply sufficient plating for the currents induced to be in the high conductivity plating.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Discharge Lamps And Accessories Thereof (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Circuit Arrangements For Discharge Lamps (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=36687872

Family Applications (1)

Country Status (9)

Cited By (1)

Families Citing this family (27)

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• 2006
  • 2006-05-30 GB GBGB0610580.3A patent/GB0610580D0/en not_active Ceased
• 2007
  • 2007-05-24 US US12/227,752 patent/US8164264B2/en active Active
  • 2007-05-24 CN CN2007800197446A patent/CN101473411B/zh not_active Expired - Fee Related
  • 2007-05-24 WO PCT/GB2007/001935 patent/WO2007138276A2/en active Application Filing
  • 2007-05-24 EA EA200870595A patent/EA012797B1/ru not_active IP Right Cessation
  • 2007-05-24 EP EP07732955A patent/EP2022078A2/de not_active Withdrawn
  • 2007-05-24 GB GB0820183A patent/GB2451208B/en not_active Expired - Fee Related
  • 2007-05-24 KR KR1020087028563A patent/KR101387991B1/ko not_active IP Right Cessation
  • 2007-05-24 MX MX2008015305A patent/MX2008015305A/es active IP Right Grant
  • 2007-05-24 JP JP2009512657A patent/JP5165678B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

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